The present invention relates to laser machining. More particularly, the present invention relates to a laser machining system and method utilizing a spatial light modulator as a programmable phase plate to modify the phase profile of a laser beam tool and thereby control a corresponding laser beam irradiance pattern produced on a target location for performing a desired machining operation on the target location.
In laser based machining applications, such as the cutting, drilling, etc. of metals or other materials, the laser beam is typically focused onto the material to be machined. Fixed phase plates are known and have been proposed as a means of modifying the shape and irradiance distribution of the laser beam to improve cutting efficiency. When placed at a chosen plane within a laser system, a fixed phase plate serves to modify the beam""s phase profile at that plane. However, when propagated to a machine tool location, e.g., the focal plane, the beam""s phase profile is changed along with a corresponding irradiance pattern produced at the machine tool location. In this manner of modifying only the phase, and not the intensity, the efficiency of the system may be preserved. Unfortunately, however, fixed phase plates are expensive to fabricate and are known to have long lead times for production. Moreover, new fixed phase plates are necessary every time the laser beam irradiance requires modification to a new size or shape.
One aspect of the invention includes a system for laser machining comprising: a laser source for propagating a laser beam toward a target location; a spatial light modulator having individual controllable elements capable of modifying a phase profile of the laser beam and producing a corresponding irradiance pattern on the target location; and a controller operably connected to the spatial light modulator for controlling the individual controllable elements so as to modify the phase profile of the laser beam into a desired phase profile and thereby produce a corresponding desired irradiance pattern on the target location capable of performing a machining operation thereon.
Another aspect of the invention includes a method for laser machining comprising: propagating a laser beam from a laser source toward a target location, the laser beam having a phase profile producing a corresponding irradiance pattern on the target location; controlling individual controllable elements of a spatial light modulator to modify the phase profile of the laser beam into a desired phase profile and thereby produce a desired irradiance pattern on the target location capable of performing a machining operation thereon; and machining the target location using the desired irradiance pattern.